Methods, systems and apparatus for controlling operation of two alternating current (ac) machines

ABSTRACT

A system is provided for controlling two AC machines. The system comprises a DC input voltage source that provides a DC input voltage, a voltage boost command control module (VBCCM), a five-phase PWM inverter module coupled to the two AC machines, and a boost converter coupled to the inverter module and the DC input voltage source. The boost converter is designed to supply a new DC input voltage to the inverter module having a value that is greater than or equal to a value of the DC input voltage. The VBCCM generates a boost command signal (BCS) based on modulation indexes from the two AC machines. The BCS controls the boost converter such that the boost converter generates the new DC input voltage in response to the BCS. When the two AC machines require additional voltage that exceeds the DC input voltage required to meet a combined target mechanical power required by the two AC machines, the BCS controls the boost converter to drive the new DC input voltage generated by the boost converter to a value greater than the DC input voltage.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The United States government has a paid-up license in this invention andthe right in limited circumstances to require the patent owner tolicense others on reasonable terms as provided by the terms of contractnumber DE-FC26-07NT43123 awarded by the United States Department ofEnergy.

TECHNICAL FIELD

The present invention generally relates to hybrid and electric vehiclepower systems, and more particularly relates to controlling operation oftwo AC machines that are part of a hybrid and electric vehicle powersystem and that are controlled by a single five-phase PWM invertermodule.

BACKGROUND OF THE INVENTION

Hybrid and electric vehicles (HEVs) typically include an alternatingcurrent (AC) electric motor which is driven by a power converter with adirect current (DC) power source, such as a storage battery. Motorwindings of the AC electric motor can be coupled to power invertermodule(s) which perform a rapid switching function to convert the DCpower to AC power which drives the AC electric motor, which in turndrives a shaft of HEV's drivetrain. Traditional HEVs implement twothree-phase pulse width modulated (PWM) inverter modules and twothree-phase AC machines (e.g., AC motors) each being driven by acorresponding one of the three-phase PWM inverter modules that it iscoupled to.

Recently, researchers have investigated the possibility of replacing thetwo three-phase pulse width modulated inverter modules with a singlefive-phase PWM inverter module that simultaneously drives both of thethree-phase AC machines. In addition, researchers have also investigatedthe possibility of using a single five-phase PWM inverter module thatdrives a first five-phase AC machine that is coupled to a secondfive-phase AC machine. One example of such research is described in apublication titled “Features of two Multi-Motor Drive Schemes Suppliedfrom Five-Phase/Five-Leg Voltage Source Inverters,” by Dujić et al., May27, 2008, which is incorporated by reference herein in its entirety.

While the possibility of using such inverter and motor configurations inHEVs is being explored, a lot of work remains to be done before theseinverter and motor configurations can actually be implemented. Oneproblem that has yet to be addressed is how to maintain the requiredoutput mechanical power of each machine while meeting voltage sharingconstraints.

Accordingly, it is desirable to provide methods, systems and apparatuscontrolling operation of two AC machines that are controlled by a singlefive-phase PWM inverter module that allow constant output power withvoltage constraint i.e. in the field-weakening region. It would also bedesirable to provide methods, systems and apparatus for increasing thevoltage used to drive the two AC machines. Furthermore, other desirablefeatures and characteristics of the present invention will becomeapparent from the subsequent detailed description and the appendedclaims, taken in conjunction with the accompanying drawings and theforegoing technical field and background.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to apparatus for it iscontrolling operation of two AC machines that are controlled by a singlefive-phase PWM inverter module.

In accordance with one embodiment, a system is provided for controllingtwo alternating current (AC) machines. The system comprises a DC inputvoltage source that provides a DC input voltage, a voltage boost commandcontrol module (VBCCM), a five-phase PWM inverter module coupled to thetwo AC machines, and a boost converter coupled to the inverter moduleand the DC input voltage source. The boost converter is designed tosupply a new DC input voltage to the inverter module having a value thatis greater than or equal to a value of the DC input voltage. The VBCCMgenerates a boost command signal that controls the boost converter suchthat the boost converter generates the new DC input voltage in responseto the boost command signal. When the two AC machines require additionalvoltage that exceeds the DC input voltage required to meet a combinedtarget mechanical power required by the two AC machines, the boostcommand signal controls the boost converter to drive the new DC inputvoltage generated by the boost converter to a value greater than the DCinput voltage.

For example, in one implementation, the voltage VBCCM can provide aboost command signal with a value equal to zero when the two AC machinesrequire voltage that is less than or equal to the DC input voltage, andin this case the new DC input voltage will be equal to original DC inputvoltage. However, when the two AC machines require additional voltage tomeet their target mechanical power that exceeds the DC input voltage,the voltage boost command signal has a value greater than zero and thenew DC input voltage is regulated to a voltage higher than the originalDC input voltage.

In one implementation, the system comprises a first control loop thatgenerates a first modulation index, and a second control loop thatgenerates a second modulation index. VBCCM receives a modulation indexreference signal, the first modulation index from the first control loopand the second modulation index from the second control loop, and addsthe first modulation index to the second modulation index to generate amodulation index feedback signal input, and then subtracts themodulation index feedback signal input from the modulation indexreference signal input to generate a modulation index error signal.Based on the modulation index error signal, the boost command signal iscalculated.

DESCRIPTION OF THE DRAWINGS

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and

FIGS. 1A-D illustrate block diagrams of a torque control system 100architecture implemented in motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention;

FIGS. 2A-C illustrate block diagrams of a torque control system 200architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention;

FIGS. 3A-3D illustrate block diagrams of a torque control system 300architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention; and

FIGS. 4A-4C illustrate block diagrams of a torque control system 400architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

As used herein, the word “exemplary” means “serving as an example,instance, or illustration.” The following detailed description is merelyexemplary in nature and is not intended to limit the invention or theapplication and uses of the invention. Any embodiment described hereinas “exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. All of the embodiments described inthis Detailed Description are exemplary embodiments provided to enablepersons skilled in the art to make or use the invention and not to limitthe scope of the invention which is defined by the claims. Furthermore,there is no intention to be bound by any expressed or implied theorypresented in the preceding technical field, background, brief summary orthe following detailed description.

Before describing in detail embodiments that are in accordance with thepresent invention, it should be observed that the embodiments resideprimarily in combinations of method steps and apparatus componentsrelated to controlling operation of two AC machines that are controlledby a single five-phase PWM inverter module. It will be appreciated thatembodiments of the invention described herein can be implemented usinghardware, software or a combination thereof. The control circuitsdescribed herein may comprise various components, modules, circuits andother logic which can be implemented using a combination of analogand/or digital circuits, discrete or integrated analog or digitalelectronic circuits or combinations thereof. As used herein the term“module” refers to a device, a circuit, an electrical component, and/ora software based component for performing a task. In someimplementations, the control circuits described herein can beimplemented using one or more application specific integrated circuits(ASICs), one or more microprocessors, and/or one or more digital signalprocessor (DSP) based circuits when implementing part or all of thecontrol logic in such circuits. It will be appreciated that embodimentsof the invention described herein may be comprised of one or moreconventional processors and unique stored program instructions thatcontrol the one or more processors to implement, in conjunction withcertain non-processor circuits, some, most, or all of the functions forcontrolling operation of two AC machines, as described herein. As such,these functions may be interpreted as steps of a method for controllingoperation of two AC machines that are controlled by a single five-phasePWM inverter module. Alternatively, some or all functions could beimplemented by a state machine that has no stored program instructions,or in one or more application specific integrated circuits (ASICs), inwhich each function or some combinations of certain of the functions areimplemented as custom logic. Of course, a combination of the twoapproaches could be used. Thus, methods and means for these functionshave been described herein. Further, it is expected that one of ordinaryskill, notwithstanding possibly significant effort and many designchoices motivated by, for example, available time, current technology,and economic considerations, when guided by the concepts and principlesdisclosed herein will be readily capable of generating such softwareinstructions and programs and ICs with minimal experimentation.

Overview

Embodiments of the present invention relate to methods and apparatus forcontrolling operation of two AC machines that are controlled by a singlefive-phase PWM inverter module. The disclosed methods and apparatus canbe implemented in operating environments where it is necessary tocontrolling operation of two AC machines that are controlled by a singlefive-phase PWM inverter module in a hybrid/electric vehicle (HEV). Inthe exemplary implementations which will now be described, the controltechniques and technologies will be described as applied to ahybrid/electric vehicle (HEV). However, it will be appreciated by thoseskilled in the art that the same or similar techniques and technologiescan be applied in the context of other systems which it is necessary tocontrol operation of two AC machines. In this regard, any of theconcepts disclosed here can be applied generally to “vehicles,” and asused herein, the term “vehicle” broadly refers to a non-living transportmechanism having an AC motor. Examples of such vehicles includeautomobiles such as buses, cars, trucks, sport utility vehicles, vans,vehicles that do not travel on land such as mechanical water vehiclesincluding watercraft, hovercraft, sailcraft, boats and ships, mechanicalunder water vehicles including submarines, mechanical air vehiclesincluding aircraft and spacecraft, mechanical rail vehicles such astrains, trams and trolleys, etc. In addition, the term “vehicle” is notlimited by any specific propulsion technology such as gasoline or dieselfuel. Rather, vehicles also include hybrid vehicles, battery electricvehicles, hydrogen vehicles, and vehicles which operate using variousother alternative fuels.

Exemplary Implementations

FIGS. 1A-D illustrate block diagrams of a torque control system 100architecture implemented in motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention. In this embodiment, the system 100 can be used to control twothree-phase AC machines 120 via a five-phase pulse width modulated (PWM)inverter module 110 connected to the two three-phase AC machines 120 sothat the two three-phase AC machines 120 share a DC input voltage (Vdc)139 available from the five-phase PWM inverter module 110 by adjustingcurrent commands that control the two three-phase AC machines 120. TheAC machines are illustrated as being permanent magnet synchronous ACmotors; however, it should be appreciated that the illustratedembodiment is only one non-limiting example of the types of AC machinesthat the disclosed embodiments can be applied to and that the disclosedembodiments can be applied to any type of AC machine. Here the term “ACmachine” generally refers to “a device or apparatus that convertselectrical energy to mechanical energy or vice versa.” AC machines cangenerally be classified into synchronous AC machines and asynchronous ACmachines. Synchronous AC machines can include permanent magnet machinesand reluctance machines. Permanent magnet machines include surface mountpermanent magnet machines (SMPMMs) and interior permanent magnetmachines (IPMMs). Asynchronous AC machines include induction machines.Although an AC machine can be an AC motor (i.e., apparatus used toconvert AC electrical energy power at its input to produce to mechanicalenergy or power), an AC machine is not limited to being an AC motor, butcan also encompass AC generators that are used to convert mechanicalenergy or power at its prime mover into electrical AC energy or power atits output. Any of the machines can be an AC motor or an AC generator.An AC motor is an electric motor that is driven by an alternatingcurrent (AC). An AC motor includes an outside stationary stator havingcoils supplied with alternating current to produce a rotating magneticfield, and an inside rotor attached to the output shaft that is given atorque by the rotating field. Depending on the type of rotor used, ACmotors can be classified as synchronous or asynchronous. A synchronousAC motor rotates exactly at the supply frequency or a sub-multiple ofthe supply frequency. The magnetic field on the rotor is eithergenerated by current delivered through slip rings or by a permanentmagnet. In implementations where the AC machine is a permanent magnetsynchronous AC motor this should be understood to encompass InteriorPermanent Magnet motors. By contrast, an asynchronous (or induction) ACmotor turns slightly slower than the supply frequency. The magneticfield on the rotor of this motor is created by an induced current.

As illustrated in FIG. 1A, the system 100 comprises a first control loop104, a second control loop 105, a Space Vector (SV) PWM module 108, thefive-phase PWM inverter module 110, a first three-phase AC machine 120-Acoupled to the five-phase PWM inverter module 110, a second three-phaseAC machine 120-B coupled to the five-phase PWM inverter module 110, anda current command adjustment module 106 coupled to the first controlloop 104 and the second control loop 105. In one non-limitingimplementation, the three-phase AC machines can be three-phase ACpowered motors.

Space Vector (SV) modulation is coupled to first control loop 104 andthe second control loop 105 and is used for the control of pulse widthmodulation (PWM). In general, the SVPWM module 108 receives voltagecommand signals 103 and generates switching vector signals 109 which itprovides to the five-phase PWM inverter module 110. In particular, theSVPWM module 108 receives a first sinusoidal voltage command (Va_1)103-A1, a second sinusoidal voltage command (Vb_1) 103-A2, a thirdsinusoidal voltage command (Vc_1) 103-A3, a fourth sinusoidal voltagecommand (Va_2) 103-A4, a fifth sinusoidal voltage command (Vb_2) 103-A5,a sixth sinusoidal voltage command (Vc_2) 103-A6, and uses these inputsto generate a first switching vector signal (Sa) 109-A, a secondswitching vector signal (Sb) 109-B, a third switching vector signal (Sc)109-C, a fourth switching vector signal (Sd) 109-D, and a fifthswitching vector signal (Se) 109-E. The particular SV modulationalgorithm implemented in the first SV PWM module 108-A can be any knownSV modulation algorithm. The switching vectors can be generated usingmodulation signals from Equation (4) from Dujic's paper (referencedabove) and comparing it with a carrier signal.

The five-phase PWM inverter module 110 is coupled to the Space Vector(SV) PWM module 108 and uses the switching vector signals 109 togenerate sinusoidal voltage signals at inverter poles 111-115. In theparticular embodiment, the five-phase PWM inverter module 110 receivesthe first switching vector signal (Sa) 109-A, the second switchingvector signal (Sb) 109-B, the third switching vector signal (Sc) 109-C,the fourth switching vector signal (Sd) 109-D, and the fifth switchingvector signal (Se) 109-E. The five-phase PWM inverter module 110includes a plurality of inverter poles including a first inverter pole111 that generates a first sinusoidal voltage (Va_*), a second inverterpole 112 that generates a second sinusoidal voltage (Vb_*), a thirdinverter pole 113 that generates a third sinusoidal voltage (Vc_*), afourth inverter pole 114 that generates a fourth sinusoidal voltage(Vd_*), and a fifth inverter pole 115 that generates a fifth sinusoidalvoltage (Ve_*).

The first three-phase AC machine 120-A is coupled to the five-phase PWMinverter module 110 via the first inverter pole 111, the second inverterpole 112 and the third inverter pole 113. The first three-phase ACmachine 120-A generates mechanical power (Torque X Speed) and a firstshaft position output (θ_r1) based on the first sinusoidal voltage(Va_*), the second sinusoidal voltage (Vb_*) and the third sinusoidalvoltage (Vc_*). In one implementation, the first shaft position output(θ_r1) can be measured via a position sensor (not illustrated) thatmeasures that angular position of the rotor of the first three-phase ACmachine 120-A.

The second three-phase AC machine 120-B is coupled to the five-phase PWMinverter module 110 via the third inverter pole 113, the fourth inverterpole 114 and the fifth inverter pole 115. In other words, the secondthree-phase AC machine 120-B and the first three-phase AC machine 120-Ashare the third inverter pole 113. The second three-phase AC machine120-B generates mechanical power (Torque X Speed) and a second shaftposition output (θ_r2) based on the third sinusoidal voltage (Vc_*), thefourth sinusoidal voltage (Vd_*) and the fifth sinusoidal voltage(Ve_*).

As will be explained in greater detail below, the current commandadjustment module 106 receives d-axis current command signals 156, andmodulation index signals 177-A, 177-B, from the first control loop 104and the second control loop 105, respectively, and torque commandsignals 136A, B and modulation index reference signal 101 and generatesadjusted d-axis and adjusted q-axis current command signals 194, 196-198based on these signals. Prior to describing the operation of the currentcommand adjustment module 106, operation of the first control loop 104and the second control loop 105 will be described.

As illustrated in FIG. 1B, the first control loop 104 includes a firststationary-to-synchronous conversion module 130-A, a firsttorque-to-current mapping module 140-A, a second summing junction 152-A,a third summing junction 162-A, a fourth summing junction 154-A, a fifthsumming junction 164-A, a first current controller module 170-A, a firstmodulation index computation module 175-A, and a firstsynchronous-to-stationary conversion module 102-A. Operation of thefirst control loop 104 will now be described.

The first stationary-to-synchronous conversion module 130-A receives afirst resultant stator current (Ias_1) 122, a second resultant statorcurrent (Ibs_1) 123, and a third resultant stator current (Ics_1) 124that are measured phase currents from motor 120-A, as well as the firstshaft position output (θ_r1) 121-A. The first stationary-to-synchronousconversion module 130-A can process or convert these stator currents122-124 along with the first shaft position output (θ_r1) 121-A togenerate a first feedback d-axis current signal (Ids_e_1) 132-A and afirst feedback q-axis current signal (Iqs_e_1) 134-A. The process ofstationary-to-synchronous conversion can be performed using Clarke andPark Transformations that are well-known in the art and for sake ofbrevity will not be described in detail. One implementation of theClarke and Park Transformations is described in “Clarke & ParkTransforms on the TMS320C2xx,” Application Report Literature Number:BPRA048, Texas Instruments, 2007, which is incorporated by referenceherein in its entirety.

The first torque-to-current mapping module 140-A receives a first torquecommand signal (Te*_1) 136-A that is input from a user of the system100, a first speed (ω1) 138-A of the shaft that is calculated based onthe derivative of the first shaft position output (θ_r1), and the DCinput voltage (Vdc) 139 as inputs. The first torque-to-current mappingmodule 140-A uses the inputs to map the first torque command signal(Te*_1) 136-A to a first d-axis current command signal (Ids_e*_1) 142-Aand a first q-axis current command signal (Iqs_e*_1) 144-A. The mappingcan be calculated using motor parameters and the following equation.

$T = {\frac{3}{2} \cdot \frac{P}{2} \cdot \lbrack {{k_{e} \cdot I_{qs}} - {( {L_{q} - L_{d}} ) \cdot I_{qs} \cdot I_{ds}}} \rbrack}$

for I_(ph)≦I_(max) and V_(ds)=r_(s)·I_(ds)−ω_(e)·L_(q)·I_(qs),V_(qs)=r_(s)·I_(qa)+ω_(e)·(L_(d)·I_(ds)+k_(e)) for V_(ph)≦K·V_(max),where I_(ph)=√{square root over (I_(ds) ²+I_(qs) ²)}, and V_(ph)=√{square root over (V_(ds) ²+V_(qs) ²)} the Ids and Iqs currentsare calculated such that torque per ampere is maximized.

Upon receiving the first d-axis current command signal (Ids_e*_1) 142-Aand an adjusted d-axis current command signal (Ids_e*_Adj_1) 196 (fromthe current command adjustment module 106), the second summing junction152-A adds the first d-axis current command signal (Ids_e*_1) 142-A toan adjusted d-axis current command signal (Ids_e*_Adj_1) 196 to generatea first new d-axis current command signal (IdsNew_e*_1) 156-A. Uponreceiving the first new d-axis current command signal (IdsNew_e*_1)156-A and a first feedback d-axis current signal (Ids_e_1) 132-A fromthe first stationary-to-synchronous conversion module 130-A, the thirdsumming junction 162-A subtracts the first feedback d-axis currentsignal (Ids_e_1) 132-A from the first new d-axis current command signal(IdsNew_e*_1) 156-A to generate a first error d-axis current signal(Idserror_e_1) 166-A.

Similarly, upon receiving the first q-axis current command signal(Iqs_e*_1) 144-A and a first adjusted q-axis current command signal(Iqs_e*_Adj_1) 197 (from the current command adjustment module 106), thefourth summing junction 154-A adds the first q-axis current commandsignal (Iqs_e*_1) 144-A to the first adjusted q-axis current commandsignal (Iqs_e*_Adj_1) 197 to generate a first new q-axis current commandsignal (IqsNew_e*_1) 158-A. The fifth summing junction 164-A thenreceives the first new q-axis current command signal (IqsNew_e*_1) 158-Aand a first feedback q-axis current signal (Iqs_e_1) 134-A from thefirst stationary-to-synchronous conversion module 130-A, and subtractsthe first feedback q-axis current signal (Iqs_e_1) 134-A from the firstnew q-axis current command signal (IqsNew_e*_1) 158-A to generate afirst error q-axis current signal (Iqserror_e_1) 168-A.

The first current controller module 170-A receives the first errord-axis current signal (Idserror_e_1) 166-A and the first error q-axiscurrent signal (Iqserror_e_1) 168-A and uses these signals to generate afirst d-axis voltage command signal (Vds_e*_1) 172-A and a first q-axisvoltage command signal (Vqs_e*_1) 174-A that are used to control orregulate current. The process of current to voltage conversion can beimplemented as a Proportional-Integral (PI) controller, which iswell-known in the art and for sake of brevity will not be described indetail.

The first modulation index computation module 175-A receives the firstd-axis voltage command signal (Vds_e*_1) 172-A and the first q-axisvoltage command signal (Vqs_e*_1) 174-A, and uses these signals togenerate a first modulation index (Mod. Index 1) 177-A. As used herein,“modulation index (MI)” can be defined via the equation

${{M\; I} = {\frac{V_{ph}}{V_{dc}} \cdot \frac{\pi}{2}}},$

where V_(ph)=√{square root over (V_(ds) ²+V_(qs) ²)}, and Vds and Vqsare the first d-axis voltage command signal (Vds_e*_1) 172-A and thefirst q-axis voltage command signal (Vqs_e*_1) 174-A output by currentcontroller 170. The range of modulation index is from 0 to 1.

The first synchronous-to-stationary conversion module 102-A receives thefirst d-axis voltage command signal (Vds_e*_1) 172-A and the firstq-axis voltage command signal (Vqs_e*_1) 174-A, and based on thesesignals, generates a first sinusoidal voltage command (Va_1) 103-A1, asecond sinusoidal voltage command (Vb_1) 103-A2, and a third sinusoidalvoltage command (Vc_1) 103-A3. The process of synchronous-to-stationaryconversion is done using inverse Clarke and Park Transformations thatare well-known in the art and for sake of brevity will not be describedin detail. One implementation of the inverse Clarke and ParkTransformations is described in the above referenced document “Clarke &Park Transforms on the TMS320C2xx.”

As illustrated in FIG. 1C, the second control loop 105 includes similarblocks or modules as the first control loop 104. The second control loop105 includes a second stationary-to-synchronous conversion module 130-B,a second torque-to-current mapping module 140-B, a sixth summingjunction 152-B, a seventh summing junction 162-B, an eighth summingjunction 154-B, a ninth summing junction 164-B, a second currentcontroller module 170-B, a second modulation index computation module175-B, and a second synchronous-to-stationary conversion module 102-B.As will now be described, the second control loop 105 operates in asimilar manner as the first control loop 104.

The second stationary-to-synchronous conversion module 130-B receivesthe third resultant stator current (Ias_2) 125, a fourth resultantstator current (Ibs_2) 126, a fifth resultant stator current (Ics_2) 127and the second shaft position output (θ_r2) 121-B, and generates, basedon these stator currents 125, 126, 127 and the second shaft positionoutput (θ_r2) 121-B, a second feedback d-axis current signal (Ids_e_2)132-B and a second feedback q-axis current signal (Iqs_e_2) 134-B.

The second torque-to-current mapping module 140-B receives a secondtorque command signal (Te*_2) 136-B that is input from a user of thesystem 100, a second speed (ω2) 138-B of the shaft, and the DC inputvoltage (Vdc) 139. The second torque-to-current mapping module 140-Bmaps the second torque command signal (Te*_2) 136-B, the second speed(ω2) 138-B of the shaft, and the DC input voltage (Vdc) 139 to a secondd-axis current command signal (Ids_e*_2) 142-B and a second q-axiscurrent command signal (Iqs_e*_2) 144-B as explained above.

The sixth summing junction 152-B receives the second d-axis currentcommand signal (Ids_e*_2) 142-B and the second adjusted d-axis currentcommand signal (Ids_e*_Adj_2) 194 (from the current command adjustmentmodule 106), and adds the second d-axis current command signal(Ids_e*_2) 142-B to the second adjusted d-axis current command signal(Ids_e*_Adj_2) 194 to generate a second new d-axis current commandsignal (Ids New_e*_2) 156-B.

The seventh summing junction 162-B receives the second new d-axiscurrent command signal (Ids New_e*_2) 156-B and the second feedbackd-axis current signal (Ids_e_2) 132-B, and subtracts the second feedbackd-axis current signal (Ids_e_2) 132-B from the second new d-axis currentcommand signal (Ids New_e*_2) 156-B to generate a second error d-axiscurrent signal (Idserror_e_1) 166-B.

The eighth summing junction 154-B receives the second q-axis currentcommand signal (Iqs_e*_2) 144-B and the second adjusted q-axis currentcommand signal (Iqs_e*_Adj_2) 198 (from the current command adjustmentmodule 106), and adds the second q-axis current command signal(Iqs_e*_2) 144-B to the second adjusted q-axis current command signal(Iqs_e*_Adj_2) 198 to generate a second new q-axis current commandsignal (IqsNew_e*_2) 158-B.

The ninth summing junction 164-B receives the second new q-axis currentcommand signal (IqsNew_e*_2) 158-B and the second feedback q-axiscurrent signal (Iqs_e_2) 134-B, and subtracts the second feedback q-axiscurrent signal (Iqs_e_2) 134-B from the second new q-axis currentcommand signal (IqsNew_e*_2) 158-B to generate a second error q-axiscurrent signal (Iqserror_e_2) 168-B.

The second current controller module 170-B receives the second errord-axis current signal (Idserror_e_2) 166-B and the second error q-axiscurrent signal (Iqserror_e_2) 168-B, and generates a second d-axisvoltage command signal (Vds_e*_2) 172-B and a second q-axis voltagecommand signal (Vqs_e*_2) 174-B. The second modulation index computationmodule 175-B receives the second d-axis voltage command signal(Vds_e*_2) 172-B and the second q-axis voltage command signal (Vqs_e*_2)174-B, and generates a second modulation index (Mod. Index 2) 177-B asdescribed above.

The second synchronous-to-stationary conversion module 102-B receivesthe second d-axis voltage command signal (Vds_e*_2) 172-B and the secondq-axis voltage command signal (Vqs_e*_2) 174-B, and generates a fourthsinusoidal voltage command (Va_2) 103-A4, a fifth sinusoidal voltagecommand (Vb_2) 103-A5 and a sixth sinusoidal voltage command (Vc_2)103-A6.

The first and the second control loop 104 and 105 respectively share theSVPWM module 108. As described above, the SVPWM module 108 receives thesinusoidal voltage commands (Va_1) 103-A1, (Vb_1) 103-A2, (Vc_1) 103-A3from the first synchronous-to-stationary conversion module 102-A, andalso receives the sinusoidal voltage command (Va_2) 103-A4, (Vb_2)103-A5, (Vc_2) 103-A6 from the second synchronous-to-stationaryconversion module 102-B, and uses these signals to generate switchingvector signals (Sa) 109-A, (Sb) 109-B, (Sc) 109-C, (Sd) 109-D, and (Se)109-E.

The five-phase PWM inverter module 110 receives the DC input voltage(Vdc) 139 and switching vector signals 109, and uses them to generatealternating current (AC) waveforms 111-115 that drive the firstthree-phase AC machine 120-A at varying speeds based on the DC inputvoltage (Vdc) 139. Although not illustrated in FIG. 1, the system 100may also include a gear coupled to and driven by the first three-phaseAC machine 120-A shaft and the second three-phase AC machine 120-Bshaft.

Operation of the current command adjustment module 106 will now bedescribed with reference to FIG. 1D. As illustrated in FIG. 1D, thecurrent command adjustment module 106 includes a first summing junction180, a voltage controller 185, a negative limiter module 190 and acurrent adjustment computation module 195. The current commandadjustment module 106 operates as follows. The first summing junction180 receives a modulation index reference signal input 101 and amodulation index feedback signal input 179, and subtracts the modulationindex feedback signal input 179 from the modulation index referencesignal input 101 to generate a modulation index error signal 181. Thevoltage controller 185 receives the modulation index error signal 181,and generates a first output command signal 186 based on the modulationindex error signal 181. In one implementation, the voltage controller185 that processes the modulation index error signal 181 can be aProportional-Integral Controller (PI). The negative limiter module 190receives the first output command signal 186 and limits the first outputcommand signal 186 between a negative value and zero. The resultinglimited value of the first output command signal 186 becomes theadjusted d-axis current command signal (Ids_e*_Adj_1) 196.

The current adjustment computation module 195 receives a first torquecommand signal (Te*_1) 136-A, a second torque command signal (Te*_2)136-B, a first new d-axis current command signal (IdsNew_e*_1) 166-A,and a second new d-axis current command signal (Ids New_e*_2) 166-B.When the current adjustment computation module 195 receives the adjustedd-axis current command signal (Ids_e*_Adj_1) 196 (i.e., when its outputby the negative limiter module 190), the current adjustment computationmodule 195 generates a second adjusted d-axis current command signal(Ids_e*_Adj_2) 194 based on the first adjusted d-axis current commandsignal (Ids_e*_Adj_1) 196, a first adjusted q-axis current commandsignal (Iqs_e*_Adj_1) 197 and a second adjusted q-axis current commandsignal (Iqs_e*_Adj_2) 198, based on the first adjusted d-axis currentcommand signal (Ids_e*_Adj_1) 196, the second adjusted d-axis currentcommand signal (Ids_e*_Adj_2) 194, the first torque command signal(Te*_1) 136-A, the second torque command signal (Te*_2) 136-B, the firstnew d-axis current command signal (IdsNew_e*_1) 166-A, and the secondnew d-axis current command signal (Ids New_e*_2) 166-B.

In one implementation, the current adjustment computation module 195 caninclude a first current adjustment computation sub-module 199-A, asecond current adjustment computation sub-module 199-B and a scalingblock (K) 199-C. The current adjustment computation sub-modules 199-A,199-B compute a derivative [dIq/dId] of the q-axis current (Tq) withrespect to the d-axis current (Id). The partial derivative [dIq/dId]with torque constant is calculated using the equation.

$T = {\frac{3}{2} \cdot \frac{P}{2} \cdot \lbrack {{k_{e} \cdot I_{qs}} - {( {L_{q} - L_{d}} ) \cdot I_{qs} \cdot I_{ds}}} \rbrack}$

for I_(ph)≦I_(max) and V_(ph)≦K·V_(max), where I_(ph)=√{square root over(I_(ds) ²+I_(qs) ²)}, the Ids and Iqs currents are calculated such thattorque per ampere is maximized with machine parameters and stored in alook-up table as function of the first torque command signal (Te*_1)136-A and the first new d-axis current command signal (IdsNew_e*_1)156-A. In one exemplary implementation, the first current adjustmentcomputation sub-module 199-A receives the first adjusted d-axis currentcommand signal (Ids_e*_Adj_1) 196 and multiplies it by the partialderivative [dIq/dId], and use these to generate the first adjustedq-axis current command signal (Iqs_e*_Adj_1) 197. The scaling block (K)receives the first adjusted d-axis current command signal (Ids_e*_Adj_1)196 and multiply it by a K factor to obtain the second adjusted d-axiscurrent command signal (Ids_e*_Adj_2) 194. The second current adjustmentcomputation sub-module 199-B can receive the second adjusted d-axiscurrent command signal (Ids_e*_Adj_2) 194, the second torque commandsignal (Te*_2) 136-B and the second new d-axis current command signal(Ids New_e*_2) 156-B and use these to generate the second adjustedq-axis current command signal (Iqs_e*_Adj_2) 198. The first adjustedd-axis current command signal (Ids_e*_Adj_1) 196, the first adjustedq-axis current command signal (Iqs_e*_Adj_1) 197, the second adjustedq-axis current command signal (Iqs_e*_Adj_2) 198 and the second adjustedd-axis current command signal (Ids_e*_Adj_2) 194 are used to modify theoriginal current command signals (i.e., the first d-axis current commandsignal (Ids_e*_1) 142-A, the first q-axis current command signal(Iqs_e*_1) 144-A, the second d-axis current command signal (Ids_e*_1)142-B and the second q-axis current command signal (Iqs_e*_2) 144-B) toallow machines 120-A, 120-B to output a given mechanical power with lessphase voltage (i.e. it allows sharing the voltage available between bothmachines without compromising output power).

FIGS. 2A-C illustrate block diagrams of a torque control system 200architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention.

As illustrated in FIG. 2A, this embodiment differs from that illustratedin FIG. 1 in that the system 200 includes two five-phase AC machines220-A, 220-B instead of two three-phase AC machine 120-A, 120-B. The twofive-phase AC machines 220-A, 220-B are coupled to each other, and thefive-phase PWM inverter module 110 is connected to one of the five-phaseAC machines 220-A, which is in turn coupled to the other one of the twofive-phase AC machines 220-B. The system 200 includes a first controlloop 204 and a second control loop 205. The first control loop 204 andthe second control loop 205 are both coupled to the five-phase PWMinverter module 110 via synchronous to stationary block 203 and SVPWMblock 209.

The five-phase PWM inverter module 110 is coupled to the Space Vector(SV) PWM module 209. The five-phase PWM inverter module 110 receives afirst switching vector signal (Sa) 109-A, a second switching vectorsignal (Sb) 109-B, a third switching vector signal (Sc) 109-C, a fourthswitching vector signal (Sd) 109-D, and a fifth switching vector signal(Se) 109-E. The five-phase PWM inverter module 110 includes a firstinverter pole 111 that outputs a first sinusoidal voltage (Va_*), asecond inverter pole 112 that outputs a second sinusoidal voltage(Vb_*), a third inverter pole 113 that outputs a third sinusoidalvoltage (Vc_*), a fourth inverter pole 114 that outputs a fourthsinusoidal voltage (Vd_*), and a fifth inverter pole 115 that outputs afifth sinusoidal voltage (Ve_*).

The first five-phase AC machine 220-A is coupled to the five-phase PWMinverter module 110 via the first inverter pole 111, the second inverterpole 112, the third inverter pole 113, the fourth inverter pole 114 andthe fifth inverter pole 115. The first five-phase AC machine 220-Agenerates output mechanical power (torque X speed) based on the firstsinusoidal voltage (Va*), the second sinusoidal voltage (Vb*), the thirdsinusoidal voltage (Vc*), the fourth sinusoidal voltage (Vd*) and thefifth sinusoidal voltage (Ve*). In addition, a first shaft positionoutput (θ_r1) 121-A can be measured from the first five-phase AC machine220-A. The first five-phase AC machine 220-A also includes a firstoutput link (a1) 222 that outputs a first output voltage, a secondoutput link (b1) 224 that outputs a second output voltage, a thirdoutput link (c1) 225 that outputs a third output voltage, a fourthoutput link (d1) 226 that outputs a fourth output voltage, and a fifthoutput link (e1) 227 that outputs a fifth output voltage. Each outputlink (a1 . . . e1) is coupled to a motor winding of the secondfive-phase AC machine 220-B so that the second five-phase AC machine220-B is coupled to the first five-phase AC machine 220-A via the firstoutput link (a1) 222, the second output link (b1) 224, the third outputlink (c1) 225, the fourth output link (d1) 226, and the fifth outputlink (e1) 227.

The second five-phase AC machine 220-B outputs its own mechanical poweroutput based on voltage at output links 222 . . . 227. Links (a2 . . .e2) that are coupled together to form a star connection in secondfive-phase AC machine 220-B. The shaft is part of each machine, themachine function is convert electrical power to mechanical power orvice-versa. The second five-phase AC machine 220-B outputs a secondshaft position output (θ_r2) 121-B.

As in the first embodiment described with reference to FIG. 1B, thefirst control loop 204 includes a first torque-to-current mapping module140-A, a second summing junction 152-A, a third summing junction 162-A,a fourth summing junction 154-A, a fifth summing junction 164-A, a firstcurrent controller module 170-A, and a first modulation indexcomputation module 175-A, as illustrated in FIG. 2B. Likewise, asillustrated in FIG. 2C, the second control loop 205 includes a secondtorque-to-current mapping module 140-B, a sixth summing junction 152-B,a seventh summing junction 162-B, an eighth summing junction 154-B, aninth summing junction 164-B, a second current controller module 170-B,and a second modulation index computation module 175-B. Each of thesejunctions and modules operates as described with reference to FIG. 1 andfor sake of brevity the description of their operation will not bedescribed here again. Moreover, the current command adjustment module106 operates in the same manner as in the first embodiment (FIGS. 1A-D),and for sake of brevity, the operation of the current command adjustmentmodule 106 will not be repeated here.

The embodiment of FIG. 2A also differs from the embodiment illustratedin FIG. 1A in that the first control loop 204 and the second controlloop 205 of the system 200 share a stationary-to-synchronous conversionmodule 231, and a synchronous-to-stationary conversion module 203.Operation of these modules will now be described.

The stationary-to-synchronous conversion module 231 is coupled to thefive-phase PWM inverter module 110 so that it receives a first resultantstator current (I_as) 122, a second resultant stator current (I_bs) 123,a third resultant stator current (I_cs) 124, a fourth resultant statorcurrent (I_ds) 126, a fifth resultant stator current (I_es) 127, a firstshaft position output (θ_r1) 121-A, and a second shaft position output(θ_r2). The stationary-to-synchronous conversion module 231 is designedto convert these stator currents 122, 123, 124, 126, 127 to generatecurrent feedback signals 132-A, 132-B, 134-A, 134-B. In particular, thestationary-to-synchronous conversion module 231 generates a firstfeedback d-axis current signal (Ids_e_1) 132-A, a first feedback q-axiscurrent signal (Iqs_e_1) 134-A, a second feedback d-axis current signal(Ids_e_1) 132-B and a second feedback q-axis current signal (Iqs_e_1)134-B, based on the first resultant stator current (I_as) 122, thesecond resultant stator current (I_bs) 123, the third resultant statorcurrent (I_cs) 124, the fourth resultant stator current (I_ds) 126, thefifth resultant stator current (I_es) 127, the first shaft positionoutput (θ_r1) 121-A, and the second shaft position output (θ_r2) byusing equations (1) through (3) below.

$\begin{matrix}{{T_{5} = {\frac{2}{5}\begin{bmatrix}1 & {\cos \; \alpha} & {\cos \; 2\; \alpha} & {\cos \; 2\; \alpha} & {\cos \; \alpha} \\0 & {\sin \; \alpha} & {\sin \; 2\; \alpha} & {{- \sin}\; 2\; \alpha} & {{- \sin}\; \alpha} \\1 & {\cos \; 2\; \alpha} & {\cos \; \alpha} & {\cos \; \alpha} & {\cos \; 2\; \alpha} \\0 & {{- \sin}\; 2\; \alpha} & {\sin \; \alpha} & {{- \sin}\; \alpha} & {\sin \; 2\; \alpha} \\{1/\sqrt{2}} & {1/\sqrt{2}} & {1/\sqrt{2}} & {1/\sqrt{2}} & {1/\sqrt{2}}\end{bmatrix}}},{{{where}\mspace{14mu} \alpha} = {2\; {\pi/5}}}} & (1) \\{{{{R_{5}(\theta)} = \begin{bmatrix}{R_{2}( \theta_{1} )} & 0 & 0 \\0 & {R_{2}( \theta_{2} )} & 0 \\0 & 0 & 1\end{bmatrix}},{where}}{{R_{2}(\theta)} = \begin{bmatrix}{\cos \; \theta} & {\sin \; \theta} \\{{- \sin}\; \theta} & {\cos \; \theta}\end{bmatrix}}} & (2) \\{I_{dq} = {R_{5} \times T_{5} \times I_{abcde}}} & (3) \\{V_{abcde} = {R_{5}^{- 1} \times T_{5}^{- 1} \times V_{dq}}} & (4)\end{matrix}$

The synchronous-to-stationary conversion module 203 receives the firstd-axis voltage command signal (Vds_e*_1) 172-A, the first q-axis voltagecommand signal (Vqs_e*_1) 174-A, the second d-axis voltage commandsignal (Vds_e*_1) 172-B, the second q-axis voltage command signal(Vqs_e*_1) 174-B, the first shaft position output (θ_r1) 121-A and thesecond shaft position output (θ_r2) 121-B. Using these inputs andequations (1), (2) and (4) above, the synchronous-to-stationaryconversion module 203 generates a first sinusoidal voltage command (Va)103-A1, a second sinusoidal voltage command (Vb) 103-A2, a thirdsinusoidal voltage command (Vc) 103-A3, a fourth sinusoidal voltagecommand (Vd) 103-A4, and a fifth sinusoidal voltage command (Ve) 103-A5.

The Space Vector (SV) PWM module 209 is coupled to thesynchronous-to-stationary conversion module 203 and receives the firstsinusoidal voltage command (Va) 103-A1, the second sinusoidal voltagecommand (Vb) 103-A2, the third sinusoidal voltage command (Vc) 103-A3,the fourth sinusoidal voltage command (Vd) 103-A4, and the fifthsinusoidal voltage command (Ve) 103-A5. Based on these inputs, the SVPWM module 209 generates a first switching vector signal (Sa) 109-A, asecond switching vector signal (Sb) 109-B, a third switching vectorsignal (Sc) 109-C, a fourth switching vector signal (Sd) 109-D, and afifth switching vector signal (Se) 109-E.

FIGS. 3A-3D illustrate block diagrams of a torque control system 300architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention.

As illustrated in FIG. 3A, the system 300 comprises a first control loop304, a second control loop 305, the five-phase PWM inverter module 110,a first three-phase AC machine 120-A coupled to the five-phase PWMinverter module 110, a second three-phase AC machine 120-B coupled tothe five-phase PWM inverter module 110, and a voltage boost commandcontrol loop 306 coupled to the first control loop 304 and the secondcontrol loop 305. The three-phase AC machines are three-phase AC poweredmotors.

The five-phase PWM inverter module 110 is coupled to SVPWM module 108.The SVPWM module 108 is coupled to the first control loop 304 and thesecond control loop 305 such that the SVPWM module 108 receivesmodulation voltage commands Va* . . . Ve*, which are compared with acarrier to generate switching vector signals Sa . . . Se 109. Thefive-phase PWM inverter module 110 receives switching vector signals 109and generates sinusoidal voltage signals. In the particular embodiment,the five-phase PWM inverter module 110 receives a first switching vectorsignal (Sa) 109-A, a second switching vector signal (Sb) 109-B, a thirdswitching vector signal (Sc) 109-C, a fourth switching vector signal(Sd) 109-D, and a fifth switching vector signal (Se) 109-E. Thefive-phase PWM inverter module 110 includes a plurality of inverterpoles including a first inverter pole 111 that outputs a firstsinusoidal voltage (Va_*), a second inverter pole 112 that outputs asecond sinusoidal voltage (Vb_*), a third inverter pole 113 that outputsa third sinusoidal voltage (Vc_*), a fourth inverter pole 114 thatoutputs a fourth sinusoidal voltage (Vd_*), and a fifth inverter pole115 that outputs a fifth sinusoidal voltage (Ve_*).

The first three-phase AC machine 120-A is coupled to the five-phase PWMinverter module 110 via the first inverter pole 111, the second inverterpole 112 and the third inverter pole 113. The first three-phase ACmachine 120-A generates mechanical power (torque X speed) and a firstshaft position output (θ_r1) based on the first sinusoidal voltage(Va_*), the second sinusoidal voltage (Vb_*) and the third sinusoidalvoltage (Vc_*).

The second three-phase AC machine 120-B is coupled to the five-phase PWMinverter module 110 via the third inverter pole 113, the fourth inverterpole 114 and the fifth inverter pole 115. In other words, the secondthree-phase AC machine 120-B and the first three-phase AC machine 120-Ashare the third inverter pole 113. The second three-phase AC machine120-B generates mechanical power (torque X speed) and a second shaftposition output (θ_r2) based on the third sinusoidal voltage (Vc_*), thefourth sinusoidal voltage (Vd_*) and the fifth sinusoidal voltage(Ve_*).

As in the embodiment described with respect to FIG. 1A, the five-phasePWM inverter module 110 can be used to control two three-phase ACmachines 120. However, this embodiment differs from that illustrated inFIG. 1A since the system 300 in FIG. 3A further includes a boostconverter 340 coupled to the five-phase PWM inverter module 110 so thata DC input voltage (Vdc) 139 can be “boosted” or increased to a boostedDC input voltage (Vdc high) 330 when the two three-phase AC machines 120require additional voltage that exceeds the DC input voltage (Vdc) 139.The boosted DC input voltage (Vdc_high) 330 can be provided to thefive-phase PWM inverter module 110 when the boost converter 340 coupledto the five-phase PWM inverter module 110 receives a boost commandsignal (VBoost_command) 320. The five-phase PWM inverter module 110 canthen use the boosted DC input voltage (Vdc_high) 330 to providesinusoidal voltages (Va_* . . . Ve_*) that have an increased voltage tothe two three-phase AC machines 120. As will be explained in greaterdetail below, the voltage boost command control loop 306 receives afirst modulation index (Mod. Index 1) 177-A and a second modulationindex (Mod. Index 2) 177-B from the first control loop 304 and thesecond control loop 305 and generates a modulation index feedback signalinput 179 based on the first modulation index (Mod. Index 1) 177-A andthe second modulation index (Mod. Index 2) 177-B.

Prior to describing the operation of the voltage boost command controlloop 306, operation of the first control loop 304 and the second controlloop 305 will be described. This embodiment differs from thatillustrated in FIGS. 1B and 1C since the first control loop 304 and thesecond control loop 305 of system 300 are somewhat simplified and usefewer summing junctions, as will now be described below.

As illustrated in FIG. 3B, the first control loop 304 includes a firststationary-to-synchronous conversion module 130-A, a firsttorque-to-current mapping module 140-A, a summing junction 152-A, asumming junction 154-A, a first current controller module 170-A, a firstmodulation index computation module 175-A, and a firstsynchronous-to-stationary conversion module 102-A. Operation of thefirst control loop 304 will now be described.

The first stationary-to-synchronous conversion module 130-A and thefirst torque-to-current mapping module 140-A operate in the same mannerdescribed above with respect to FIG. 1 and for sake of brevity theirrespective operation will not be described again.

In this embodiment, upon receiving the first d-axis current commandsignal (Ids_e*_1) 142-A and the first feedback d-axis current signal(Ids_e_1) 132-A, the summing junction 152-A subtracts the first feedbackd-axis current signal (Ids_e_1) 132-A from the first d-axis currentcommand signal (Ids_e*_1) 142-A to generate a first error d-axis currentsignal (Idserror_e_1) 166-A. Similarly, upon receiving the first q-axiscurrent command signal (Iqs_e*_1) 144-A and the first feedback q-axiscurrent signal (Iqs_e_1) 134-A, the summing junction 154-A subtracts thefirst feedback q-axis current signal (Iqs_e_1) 134-A from the firstq-axis current command signal (Iqs_e*_1) 144-A to generate a first errorq-axis current signal (Iqserror_e_1) 168-A.

The first current controller module 170-A receives the first errord-axis current signal (Idserror_e_1) 166-A and the first error q-axiscurrent signal (Iqserror_e_1) 168-A and uses these signals to generate afirst d-axis voltage command signal (Vds_e*_1) 172-A and a first q-axisvoltage command signal (Vqs_e*_1) 174-A.

The first modulation index computation module 175-A, and the firstsynchronous-to-stationary conversion module 102-A operate in the samemanner described above with respect to FIG. 1 and for sake of brevitytheir respective operation will not be described again.

As illustrated in FIG. 3C, the second control loop 305 includes similarblocks or modules as the first control loop 304. The second control loop305 includes a second stationary-to-synchronous conversion module 130-B,a second torque-to-current mapping module 140-B, a summing junction152-B, summing junction 154-B, a second current controller module 170-B,a second modulation index computation module 175-B, and a secondsynchronous-to-stationary conversion module 102-B. As will now bedescribed, the second control loop 305 operates in a similar manner asthe first control loop 304.

The second stationary-to-synchronous conversion module 130-B, and thesecond torque-to-current mapping module 140-B operate in the same mannerdescribed above with respect to FIG. 1 and for sake of brevity theirrespective operation will not be described again.

The summing junction 152-B receives the second d-axis current commandsignal (Ids_e*_2) 142-B and the second feedback d-axis current signal(Ids_e_1) 132-B, and subtracts the second feedback d-axis current signal(Ids_e_1) 132-B from the second d-axis current command signal (Ids_e*_2)142-B to generate a second error d-axis current signal (Idserror_e_2)166-B.

The summing junction 154-B receives the second q-axis current commandsignal (Iqs_e*_2) 144-B and the second feedback q-axis current signal(Iqs_e_2) 134-B, and subtracts the second feedback q-axis current signal(Iqs_e_2) 134-B from the second q-axis current command signal (Iqs_e*_2)144-B to generate a second error q-axis current signal (Iqserror_e_2)168-B.

The second current controller module 170-B receives the second errord-axis current signal (Idserror_e_2) 166-B and the second error q-axiscurrent signal (Iqserror_e_2) 168-B, and generates a second d-axisvoltage command signal (Vds_e*_1) 172-B and a second q-axis voltagecommand signal (Vqs_e*_1) 174-B.

The second modulation index computation module 175-B, and the secondsynchronous-to-stationary conversion module 102-B operate in the samemanner described above with respect to FIG. 1 and for sake of brevitytheir respective operation will not be described again.

Operation of the voltage boost command control loop 306 will now bedescribed with reference to FIG. 3D. As illustrated in FIG. 3D, thevoltage boost command control loop 306 includes a summing junction 180,a voltage controller 312, and a negative limiter module 360. The voltageboost command control loop 306 operates as follows. The summing junction180 receives a modulation index reference signal input 101 and amodulation index feedback signal input 179, and subtracts the modulationindex reference signal input 101 from the modulation index feedbacksignal input 179 from to generate a modulation index error signal 181.The voltage controller 312 receives the modulation index error signal181, and generates a first output command signal 186 based on themodulation index error signal 181 using a Proportional-Integral (PI)controller. The positive limiter module 316 receives the first outputcommand signal 186, and allows the first output command signal 186 topass when it is in the range from zero to a positive value. The outputof the positive limiter module 316 becomes the voltage boost commandsignal (V_Boost_Cmd) 320 based on the first output command signal 186.

When the voltage boost command signal (V_Boost_Cmd) 320 is generated bythe voltage command controller 310, it is supplied to the boostconverter 340. When the voltage boost command signal (V_Boost_Cmd) 320received by the boost converter 340 is equal to zero, the boostconverter provides the normal DC input voltage (Vdc) 139 to thefive-phase PWM inverter module 110. When the two three-phase AC machines120 require additional voltage that exceeds the DC input voltage (Vdc)139 required to meet a combined target mechanical power required by thetwo three-phase AC machines 120, the voltage command controller 310 willgenerate the voltage boost command signal (V_Boost_Cmd) 320 thatcontrols the boost converter 340 such that the boost converter 340generates the new boosted DC input voltage (Vdc_high) in response to thevoltage boost command signal (V_Boost_Cmd) 320 that has a value greaterthan the normal DC input voltage (Vdc) 139. When the voltage boostcommand signal (V_Boost_Cmd) 320 received by the boost converter 340 isgreater than zero, it increases or “boosts” the DC input voltage (Vdc)139 and provides a boosted DC input voltage (Vdc_high) 330 to thefive-phase PWM inverter module 110. The five-phase PWM inverter module110 can then use the boosted DC input voltage (Vdc_high) 330 to providesinusoidal voltages (Va_* . . . Ve_*) that have an increased voltage tothe two three-phase AC machines 120.

Thus, the five-phase PWM inverter module 110 receives the switchingvector signals 109 and the boosted DC input voltage (Vdc_high) 330,which can be equal to the normal DC input voltage (Vdc) 139 or higher,and uses it to generate sinusoidal voltage waveforms on links 111-115that drive the first three-phase AC machines 120-A, 120-B at varyingspeeds.

Although not illustrated in FIG. 3A, the system 300 also includes a gearcoupled to and driven by the first three-phase AC machine 120-A shaftand the second three-phase AC machine 120-B shaft.

FIGS. 4A-4C illustrate block diagrams of a torque control system 400architecture implemented in a motor drive system of a hybrid/electricvehicle (HEV) according to one exemplary implementation of the presentinvention.

As illustrated in FIG. 4A, this embodiment differs from that illustratedin FIG. 3A in that the system 400 includes two five-phase AC machines220-A, 220-B instead of two three-phase AC machines 120-A, 120-B. Thetwo five-phase AC machines 220-A, 220-B are coupled to each other, andthe five-phase PWM inverter module 110 is connected to one of thefive-phase AC machines 220-A, which is in turn coupled to the other oneof the five-phase AC machines 220-B. The system 400 includes a firstcontrol loop 304 and a second control loop 305. The first control loop304 and the second control loop 305 are both coupled to the five-phasePWM inverter module 110. The embodiment of FIG. 4A also differs from theembodiment illustrated in FIG. 3A in that the first control loop 304 andthe second control loop 305 of the system 400 share astationary-to-synchronous conversion module 231, and asynchronous-to-stationary conversion module 203. Operation of thesemodules is the same as described above with respect to FIGS. 2A-2C andfor sake of brevity their respective operation will not be describedagain.

The five-phase PWM inverter module 110 is coupled to the Space Vector(SV) PWM module 209. The five-phase PWM inverter module 110 receives afirst switching vector signal (Sa) 109-A, a second switching vectorsignal (Sb) 109-B, a third switching vector signal (Sc) 109-C, a fourthswitching vector signal (Sd) 109-D, and a fifth switching vector signal(Se) 109-E. The five-phase PWM inverter module 110 includes a firstinverter pole 111 that outputs a first sinusoidal voltage (Va_*), asecond inverter pole 112 that outputs a second sinusoidal voltage(Vb_*), a third inverter pole 113 that outputs a third sinusoidalvoltage (Vc_*), a fourth inverter pole 114 that outputs a fourthsinusoidal voltage (Vd_*), and a fifth inverter pole 115 that outputs afifth sinusoidal voltage (Ve_*).

The first five-phase AC machine 220-A is coupled to the five-phase PWMinverter module 110 via the first inverter pole 111, the second inverterpole 112, the third inverter pole 113, the fourth inverter pole 114 andthe fifth inverter pole 115. The first five-phase AC machine 220-Agenerates output mechanical power (torque X speed) based on the firstsinusoidal voltage (Va_*), the second sinusoidal voltage (Vb_*), thethird sinusoidal voltage (Vc_*), the fourth sinusoidal voltage (Vd_*)and the fifth sinusoidal voltage (Ve_*). In addition, a first shaftposition output (θ_r1) 121-A can be measured from the first five-phaseAC machine 220-A. The first five-phase AC machine 220-A also includes afirst output link (a1) 222 that outputs a first output voltage, a secondoutput link (b1) 224 that outputs a second output voltage, a thirdoutput link (c1) 225 that outputs a third output voltage, a fourthoutput link (d1) 226 that outputs a fourth output voltage, and a fifthoutput link (e1) 227 that outputs a fifth output voltage. Each outputlink (a1 . . . e1) is coupled to a motor winding of the secondfive-phase AC machine 220-B so that the second five-phase AC machine220-B is coupled to the first five-phase AC machine 220-A via the firstoutput link (a1) 222, the second output link (b1) 224, the third outputlink (c1) 225, the fourth output link (d1) 226, and the fifth outputlink (e1) 227.

The second five-phase AC machine 220-B outputs its own output mechanicalpower based on voltage at output links 222 . . . 227. Links (a2 . . .e2) that are coupled together to form a star connection in machine220-B. The second five-phase AC machine 220-B outputs a second shaftposition output (θ_r2) 121-B.

As in the third embodiment described with reference to FIG. 3B, thefirst control loop 304 includes a first torque-to-current mapping module140-A, a summing junction 152-A, a summing junction 154-A, a firstcurrent controller module 170-A, and a first modulation indexcomputation module 175-A, as illustrated in FIG. 4B. Likewise, asillustrated in FIG. 4C, the second control loop 305 includes a secondtorque-to-current mapping module 140-B, a summing junction 152-B, asumming junction 154-B, a second current controller module 170-B, and asecond modulation index computation module 175-B. Each of thesejunctions and modules operates as described with reference to FIGS. 3Band 3C and for sake of brevity the description of their operation willnot be described here again. Moreover, the voltage boost command controlloop 306 operates in the same manner as in the third embodiment (FIG.3D), and for sake of brevity, the operation of the voltage boost commandcontrol loop 306 will not be repeated here.

Some of the embodiments and implementations are described above in termsof functional and/or logical block components and various processingsteps. However, it should be appreciated that such block components maybe realized by any number of hardware, software, and/or firmwarecomponents configured to perform the specified functions. For example,an embodiment of a system or a component may employ various integratedcircuit components, e.g., memory elements, digital signal processingelements, logic elements, look-up tables, or the like, which may carryout a variety of functions under the control of one or moremicroprocessors or other control devices. In addition, those skilled inthe art will appreciate that embodiments described herein are merelyexemplary implementations.

In this document, relational terms such as first and second, and thelike may be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions.Furthermore, depending on the context, words such as “connect” or“coupled to” used in describing a relationship between differentelements do not imply that a direct physical connection must be madebetween these elements. For example, two elements may be connected toeach other physically, electronically, logically, or in any othermanner, through one or more additional elements.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the exemplary embodiment or exemplary embodiments. Itshould be understood that various changes can be made in the functionand arrangement of elements without departing from the scope of theinvention as set forth in the appended claims and the legal equivalentsthereof.

1. A system for controlling two alternating current (AC) machines, thesystem comprising: a five-phase PWM inverter module coupled to the twoAC machines and being designed to generate sinusoidal voltages for thetwo AC machines; a DC input voltage source that provides a DC inputvoltage; a boost converter, coupled to the five-phase PWM invertermodule and the DC input voltage source, and being designed to supply anew DC input voltage to the five-phase PWM inverter module having avalue that is greater than or equal to a value of the DC input voltage;and a voltage boost command control module designed to generate a boostcommand signal that controls the boost converter such that the boostconverter generates the new DC input voltage in response to the boostcommand signal, wherein the boost command signal drives the new DC inputvoltage generated by the boost converter to a value greater than the DCinput voltage when the two AC machines require additional voltage thatexceeds the DC input voltage required to meet a combined targetmechanical power required by the two AC machines.
 2. A system accordingto claim 1, wherein the voltage boost command control module is furtherdesigned to: output the voltage boost command signal with a positivevalue to the boost converter when the two AC machines require additionalvoltage that exceeds the DC input voltage, and output the voltage boostcommand signal with a zero value to the boost converter when the voltagerequired by the two AC machines is less than or equal to the DC inputvoltage, and wherein the five-phase PWM inverter module generates, basedon the new DC input voltage, sinusoidal voltage waveforms that drive thetwo AC machines at varying speeds.
 3. A system according to claim 1,further comprising: a first control loop designed to map a first torquecommand signal, a first speed (ω1) of a shaft, and the new DC inputvoltage to a first d-axis current command signal and a first q-axiscurrent command signal; a second control loop designed to map a secondtorque command signal, a second speed (ω2) of the shaft, and the new DCinput voltage to a second d-axis current command signal and a secondq-axis current command signal; wherein the voltage boost command controlmodule is further designed to receive a modulation index referencesignal, a first modulation index from the first control loop and asecond modulation index from the second control loop, and add the firstmodulation index to the second modulation index to generate a modulationindex feedback signal input; and subtract the modulation index referencesignal input from the modulation index feedback signal input to generatea modulation index error signal.
 4. A system according to claim 3,wherein the voltage boost command control module is designed to operatein conjunction with the first control loop and the second control loopand further comprises: a voltage command controller, comprising: avoltage controller designed to: receive the modulation index errorsignal; and generate a first output command signal based on themodulation index error signal; a positive limiter module designed to:receive the first output command signal, and limit the first outputcommand signal between zero and a positive value, wherein the positivelimiter module outputs the boost command signal to the boost converter,wherein the boost command signal controls the boost converter such thatthe boost converter supplies a voltage greater than the DC input voltageto the five-phase PWM inverter module when the two AC machines requireadditional voltage that exceeds the DC input voltage, and wherein theboost command signal outputs a zero value to the boost converter whenthe first output command signal is less than or equal to zero so thatthe boost converter supplies the DC input voltage to the five-phase PWMinverter module when the voltage required by the two AC machines is lessthan or equal to the DC input voltage.
 5. A system according to claim 3,wherein the two AC machines comprise: a first three-phase AC machine anda second three-phase AC machine, and wherein the first control loopcomprises: a first torque-to-current mapping module designed to: receivethe first torque command signal, the first speed (ω1) of the shaft, andthe new DC input voltage, and to map the first torque command signal,the first speed (ω1) of the shaft, and new DC input voltage to the firstd-axis current command signal and the first q-axis current commandsignal; a first stationary-to-synchronous conversion module designed to:receive a first resultant stator current, a second resultant statorcurrent, a third resultant stator current that are measured phasecurrents from the first three-phase AC machine and the first shaftposition output (θ_r1); and generate a first feedback d-axis currentsignal and a first feedback q-axis current signal based on the firstresultant stator current, the second resultant stator current, the thirdresultant stator current and the first shaft position output (θ_r1); afirst summing junction designed to: receive the first d-axis currentcommand signal and the first feedback d-axis current signal; andsubtract the first feedback d-axis current signal from the first d-axiscurrent command signal to generate a first error d-axis current signal;and a second summing junction designed to: receive the first q-axiscurrent command signal and a first feedback q-axis current signal; andsubtract the first feedback q-axis current signal from the first q-axiscurrent command signal to generate a first error q-axis current signal.6. A system according to claim 5, wherein the first control loop furthercomprises: a first current controller module designed to: receive thefirst error d-axis current signal and the first error q-axis currentsignal; and generate a first d-axis voltage command signal and a firstq-axis voltage command signal; a first modulation index computationmodule designed to: receive the first d-axis voltage command signal andthe first q-axis voltage command signal; and generate the firstmodulation index; and a first synchronous-to-stationary conversionmodule designed to: receive the first d-axis voltage command signal, thefirst q-axis voltage command signal and the first shaft position output(θ_r1); and generate a first sinusoidal voltage command, a secondsinusoidal voltage command, a third sinusoidal voltage command.
 7. Asystem according to claim 6 wherein the second control loop furthercomprises: a second torque-to-current mapping module designed to:receive a second torque command signal, a second speed (ω2) of theshaft, and the new DC input voltage; and map the second torque commandsignal, the second speed (ω2) of the shaft, and the new DC input voltageto a second d-axis current command signal and a second q-axis currentcommand signal; a second stationary-to-synchronous conversion moduledesigned to: receive a fourth resultant stator current, a fifthresultant stator current and a sixth resultant stator current that aremeasured phase currents from the second three-phase AC machine and asecond shaft position output (θ_r2); and generate a second feedbackd-axis current signal and a second feedback q-axis current signal basedon the fourth resultant stator current, the fifth resultant statorcurrent, the sixth resultant stator current that are measured phasecurrents from the second three-phase AC machine and the second shaftposition output (θ_r2). a third summing junction designed to: receivethe second d-axis current command signal and the second feedback d-axiscurrent signal; and subtract the second feedback d-axis current signalfrom the second d-axis current command signal to generate a second errord-axis current signal; and a fourth summing junction designed to:receive the second q-axis current command signal and the second feedbackq-axis current signal; and subtract the second feedback q-axis currentsignal from the second q-axis current command signal to generate asecond error q-axis current signal.
 8. A system according to claim 7,wherein the second control loop further comprises: a second currentcontroller module designed to: receive the second error d-axis currentsignal and the second error q-axis current signal; and generate a secondd-axis voltage command signal and a second q-axis voltage commandsignal; a second modulation index computation module designed to:receive the second d-axis voltage command signal and the second q-axisvoltage command signal; and generate a second modulation index; and asecond synchronous-to-stationary conversion module designed to: receivethe second d-axis voltage command signal and the second q-axis voltagecommand signal; and generate a fourth sinusoidal voltage command, afifth sinusoidal voltage command and a sixth sinusoidal voltage command.9. A system according to claim 1, the system further comprising: a SpaceVector (SV) PWM module, coupled to the first control loop and the secondcontrol loop and designed to receive the first sinusoidal voltagecommand, the second sinusoidal voltage command, the third sinusoidalvoltage command, the fourth sinusoidal voltage command, the fifthsinusoidal voltage command, and the sixth sinusoidal voltage command;and generate a first switching vector signal, a second switching vectorsignal, a third switching vector signal, a fourth switching vectorsignal, and a fifth switching vector signal; wherein the five-phase PWMinverter module is coupled to the SVPWM module and designed to receivethe first switching vector signal, the second switching vector signal,the third switching vector signal, the fourth switching vector signal,and the fifth switching vector signal, and further comprises: a firstinverter pole that outputs a first sinusoidal voltage, a second inverterpole that outputs a second sinusoidal voltage, a third inverter polethat outputs a third sinusoidal voltage, a fourth inverter pole thatoutputs a fourth sinusoidal voltage, and a fifth inverter pole thatoutputs a fifth sinusoidal voltage; wherein the first three-phase ACmachine is coupled to the five-phase PWM inverter module via the firstinverter pole, the second inverter pole and the third inverter pole anddesigned to generate first mechanical power based on the firstsinusoidal voltage, the second sinusoidal voltage and the thirdsinusoidal voltage, and the first shaft position output (θ_r1); whereinthe second three-phase AC machine coupled to the five-phase PWM invertermodule via the third inverter pole, the fourth inverter pole and thefifth inverter pole, and designed to generate second mechanical powerbased on the third sinusoidal voltage, the fourth sinusoidal voltage andthe fifth sinusoidal voltage and the second shaft position output(θ_r2); and a first shaft coupled to and driven by the first mechanicalpower output by the first three-phase AC machine and a second shaft bythe second mechanical power output by the second three-phase AC machine.10. A system according to claim 3, further comprising: astationary-to-synchronous conversion module designed to: receive a firstresultant stator current, a second resultant stator current, a thirdresultant stator current, a fourth resultant stator current, a fifthresultant stator current, a first shaft position output, and a secondshaft position output, and designed to generate a first feedback d-axiscurrent signal, a first feedback q-axis current signal, a secondfeedback d-axis current signal and a second feedback q-axis currentsignal; and a synchronous-to-stationary conversion module designed to:receive a first d-axis voltage command signal, a first q-axis voltagecommand signal, a second d-axis voltage command signal and a secondq-axis voltage command signal, the first shaft position output, and thesecond shaft position output; and generate a first sinusoidal voltagecommand, a second sinusoidal voltage command, a third sinusoidal voltagecommand, a fourth sinusoidal voltage command, and a fifth sinusoidalvoltage command.
 11. A system according to claim 10, wherein the two ACmachines comprise: a first five-phase AC machine coupled to a secondfive-phase AC machine, and wherein the first control loop comprises: afirst torque-to-current mapping module designed to: receive the firsttorque command signal, the first speed (ω1) of the shaft, and the new DCinput voltage, and to map the first torque command signal, the firstspeed (ω1) of the shaft, and the new DC input voltage to the firstd-axis current command signal and the first q-axis current commandsignal; a first summing junction designed to: receive the first d-axiscurrent command signal and the first feedback d-axis current signal; andsubtract the first feedback d-axis current signal from the first d-axiscurrent command signal to generate a first error d-axis current signal;and a second summing junction designed to: receive the first q-axiscurrent command signal and the first feedback q-axis current signal; andsubtract the first feedback q-axis current signal from the first q-axiscurrent command signal to generate a first error q-axis current signal.12. A system according to claim 11, wherein the first control loopfurther comprises: a first current controller module designed to:receive the first error d-axis current signal and the first error q-axiscurrent signal; and generate a first d-axis voltage command signal and afirst q-axis voltage command signal; and a first modulation indexcomputation module designed to: receive the first d-axis voltage commandsignal and the first q-axis voltage command signal; and generate thefirst modulation index.
 13. A system according to claim 12, wherein thesecond control loop further comprises: a second torque-to-currentmapping module designed to: receive a second torque command signal, asecond speed (ω2) of the shaft, and the new DC input voltage; and mapthe second torque command signal, the second speed (ω2) of the shaft,and the new DC input voltage to a second d-axis current command signaland a second q-axis current command signal; a third summing junctiondesigned to: receive the second d-axis current command signal and thesecond feedback d-axis current signal; and subtract the second feedbackd-axis current signal from the second d-axis current command signal togenerate a second error d-axis current signal; and a fourth summingjunction designed to: receive the second q-axis current command signaland the second feedback q-axis current signal; and subtract the secondfeedback q-axis current signal from the second q-axis current commandsignal to generate a second error q-axis current command signal.
 14. Asystem according to claim 13, wherein the second control loop furthercomprises: a second current controller module designed to: receive thesecond error d-axis current signal and the second error q-axis currentsignal; and generate a second d-axis voltage command signal and a secondq-axis voltage command signal; and a second modulation index computationmodule designed to: receive the second d-axis voltage command signal andthe second q-axis voltage command signal; and generate a secondmodulation index.
 15. A system according to claim 14, the system furthercomprising: a Space Vector (SV) PWM module, coupled to the first controlloop, the second control loop via the synchronous-to-stationaryconversion module, and the five-phase PWM inverter module, the SVPWMmodule being designed to receive the first sinusoidal voltage command,the second sinusoidal voltage command, the third sinusoidal voltagecommand, the fourth sinusoidal voltage command, and the fifth sinusoidalvoltage command; and generate a first switching vector signal, a secondswitching vector signal, a third switching vector signal, a fourthswitching vector signal, and a fifth switching vector signal; whereinthe five-phase PWM inverter module is coupled to the SVPWM module anddesigned to receive the first switching vector signal, the secondswitching vector signal, the third switching vector signal, the fourthswitching vector signal, and the fifth switching vector signal, whereinthe five-phase PWM inverter module comprises: a first inverter pole thatoutputs a first sinusoidal voltage, a second inverter pole that outputsa second sinusoidal voltage, a third inverter pole that outputs a thirdsinusoidal voltage, a fourth inverter pole that outputs a fourthsinusoidal voltage, and a fifth inverter pole that outputs a fifthsinusoidal voltage; wherein the first five-phase AC machine is coupledto the five-phase PWM inverter module via the first inverter pole, thesecond inverter pole and the third inverter pole, the fourth inverterpole and the fifth inverter pole, and is designed to generate firstthrough fifth machine voltages and to generate mechanical power based onfirst to fifth machine voltage; and a first shaft coupled to and drivenby the mechanical power output by the first five-phase AC machine,wherein the second five-phase AC machine coupled in series to the firstfive-phase AC machine, and is designed to generate mechanical powerbased on the first through fifth machine voltages; and a second shaftcoupled to and driven by the mechanical power output by the secondfive-phase AC machine.
 16. A system, comprising: two alternating current(AC) machines that require a combined target mechanical power thatvaries during operation; a five-phase PWM inverter module coupled to thetwo AC machines and being designed to generate sinusoidal voltagewaveforms for the two AC machines at varying speeds; a DC input voltagesource that provides a DC input voltage; a boost converter, coupled tothe five-phase PWM inverter module and the DC input voltage source, andbeing designed to supply a new DC input voltage to the five-phase PWMinverter module having a value that is greater than or equal to a valueof the DC input voltage, wherein the five-phase PWM inverter modulegenerates the sinusoidal voltage waveforms that drive the two ACmachines based on the new DC input voltage; and a voltage boost commandcontrol module designed to generate a boost command signal that controlsthe boost converter.
 17. A system according to claim 16, wherein theboost command signal generated by the voltage boost command controlmodule controls the boost converter such that the boost convertergenerates the new DC input voltage in response to the boost commandsignal.
 18. A system according to claim 17, wherein the boost commandsignal drives the new DC input voltage generated by the boost converterto a value greater than the DC input voltage when the two AC machinesrequire additional voltage that exceeds the DC input voltage required tomeet the combined target mechanical power required by the two ACmachines.
 19. A system according to claim 18, wherein the voltage boostcommand control module is further designed to: output the voltage boostcommand signal with a positive value to the boost converter when the twoAC machines require additional voltage that exceeds the DC inputvoltage, and output the voltage boost command signal with a zero valueto the boost converter when the voltage required by the two AC machinesis less than or equal to the DC input voltage.
 20. A system according toclaim 16, further comprising: a first control loop; and a second controlloop, wherein the voltage boost command control module is designed tooperate in conjunction with the first control loop and the secondcontrol loop, and wherein the voltage boost command control module isfurther designed to receive a modulation index reference signal, a firstmodulation index from the first control loop and a second modulationindex from the second control loop, and add the first modulation indexto the second modulation index to generate a modulation index feedbacksignal input; and subtract the modulation index reference signal inputfrom the modulation index feedback signal input to generate a modulationindex error signal, wherein the voltage boost command control modulefurther comprises: a voltage command controller, comprising: a voltagecontroller designed to: receive the modulation index error signal; andgenerate a first output command signal based on the modulation indexerror signal; a positive limiter module designed to: receive the firstoutput command signal, and limit the first output command signal betweenzero and a positive value, wherein the positive limiter module outputsthe boost command signal to the boost converter, wherein the boostcommand signal controls the boost converter such that the boostconverter supplies a voltage greater than the DC input voltage to thefive-phase PWM inverter module when the two AC machines requireadditional voltage that exceeds the DC input voltage, and wherein theboost command signal outputs a zero value to the boost converter whenthe first output command signal is less than or equal to zero so thatthe boost converter supplies the DC input voltage to the five-phase PWMinverter module when the voltage required by the two AC machines is lessthan or equal to the DC input voltage.